Although some promising data have been obtained in studies attempting to ameliorate experimental or clinical Parkinsonism, the technique of neural transplantation is still in its infancy. Controversy surrounds many issues in the field. This Core Unit is well situated to tackle some of these important questions. Biochemical and pharmacological techniques, including HPLC, GC-MS, autoradiography, and radioimmunoassay will be used to study; the factors that may influence the survival of fetal dopamine cells destined for transplantation, the functioning and growth of graft fibers following transplantation, the integration of the grafted cells with the host brain, the mechanism underlying the behavioral effects of transplantation, and ways to improve both the model of Parkinson's disease and the cells that are implanted. In addition, new approaches and techniques will be implemented as they become available. The Core pioneered the potential of novel cocaine analogs as highly sensitive markers for dopamine neurons. Quantitative autoradiography using two such analogs has yielded new insights into graft function in the striatum of the MPTP-treated monkey and contributed a useful ligand for imaging studies also now in progress.